Drawer lock joints

[LCHIEN]

Anybody have any experience with drawer (front) lock bits?

I was investigating them as alternatives to box joints, dovetails and rabbet joints.
They have multiple surfaces to glue joint and can be cut with one bit and maybe one router height and depth if you do it right. One pass on each side of the joint Gives you interlocking joint with a lot of glue area in three different planes for srength.





One board is cut (the drawer front and back) with the wood horizontal on the router table and the other (sides) with the wood vertical against the fence.
It took me a little while to get my brain around it.

It was a little sloppier than I expected, maybe because I was using some soft cedar scraps. On the other hand, it's pretty easy to glue up - clamping across the sides basically locks the joint together, it is not going to slip and slide away. I put a small assembly square in one corner to square the whole thing up.

Of course you can adjust the depth and get an overlapping drawer front to hide drawer slide hardware.

[LCHIEN]

Here's the cut made with the front of the box/drawer with the board horizontal on the table



Here's the cut made on the sides of the drawer/box with the board vertical



The inside of the box is always facing the router bit table or fence.

[d_meister]

I have one of those bits, and they are fiddly to set up. The key is to make a setup template block after you've accomplished the correct setup for the particular thickness of material you're using. Then you can get the setup back if you need to change bits or fence positions. There are no universal templates, so plywood and dimensional lumber would need unique setup templates that are thickness specific. Rockler has setup blocks for specific thicknesses made from UHMW. I made one years ago, but I don't know where it is Moving house didn't help, and it looks like scrap, anyway. I tried using my bit on the drawers in the sanding tool center I recently made, and the Home Depot Exclusive tropical "hardwood" plywood just disintegrated with the bit. I tried initial shallow cuts and taped cut-lines, but the edge on the stuff had more in common with a toothbrush than a fine furniture joint afterwards, so choice of material is vital to acceptable results.
Another issue is the inherent opportunity for material use error in that you're not using easy full length material dimensions like you can with miters or through-dovetails. It can result in the box being longer than planned in one direction due to an oversight (undersight?). There can also be different finished lengths by material in that the bit height will alter the overlap thickness in what would usually be the end piece. It is a strong joint in the pulling direction and easy to clamp, though.
I ended up doing miter joints with diagonal cross dowels, as the "exclusive" plywood cut cleanly with a good saw blade. The ply didn't like straight router bits much, either.
Generally, my go-to is box joints with a router jig. Better the devil you know......

[mpc]

I use a "lock joint" that is just tongue-and-dado based, pretty much what you see on the Woodsmith TV show. Slots/dados can be made with dado blades on the table saw or on the router with straight/spiral bits or slot cutting bits.

I use a 1/4 inch spiral bit to make the dados in the drawer sides though a dado stack in the table saw works just as well. Setup is fairly easy: the router table fence is positioned so the distance between it and the far end of the bit matches the thickness of the drawer front and rear pieces. The bit height, which becomes the dado depth, is 1/4 inch which makes the math easy to determine drawer front/back lengths = take the desired drawer width minus the combined thickness of the two drawer sides and then add 1/2 inch. A router bit or table saw dado stack can be used to make the rabbets in the drawer front and back. I use dado blades and a sacrificial fence face on the rip fence. A router table with a slot cutting bit can make these cuts as well though you'd have to hold the drawer side pieces vertically, against the fence, to make the dado cuts.



The final joint, visible on the right side in the picture, was made with so-called 3/4 inch Baltic Birch plywood for the drawer sides, the drawer fronts and backs are 1/2 inch Baltic Birch plywood. A 3/4 inch Baltic Birch drawer face piece was added later. The final joint looks very much like a squared-off version of the joint produced by the router bit in the original post/question. I use the same router table and straight bit setup to route the grooves for the drawer bottom. I use 1/2 inch thick plywood, sometimes 3/8ths, for draw bottoms (for extra strength/minimal sag bottoms) with a rabbet along all 4 edges.

Loring's third picture shows a drawer front that extends past the drawer sides - something the posted router bit can do easily. My example drawer, with the add-on drawer front, accomplishes the same thing with a rather thick final drawer front which is okay for shop furniture but not ideal for fine furniture. Hogging off most of the end of the drawer front, using a dado stack or tenoning jig on the table saw, followed by a table mounted slot cutting router bit, could make the joint. You'd have to make the drawer front first, then fit the drawer side dado to it however.

This is one of my shop drawers - with chisels and a few small hand planes. It sees a lot of use and, after a dozen years, shows no signs of failure. I use basic Tightbond II or III glue for my shop cabinets. My shop cabinets are plywood... this joint causes much less tear-out compared to box joints and dovetails joint tests that I tried. Dovetails in plywood --> that was a miserable test!

To answer Loring's initial question: No, I've never tried the drawer lock router bit that would make these joints using just the router. But, while typing this reply, I realized a slot cutting bit would be a good option and would be used/setup pretty much the same way as the drawer lock bit.

mpc

[leehljp]

That is basically the way that I make mine.